Motor and Boat question.

[reds10]

stepdad just bought a 1984 Cajun, 20ft with a 220 hp yam on it.

Wondering if anyone could give me any insight to this boat. dual console, metalic grey paint, motor runs perfect.

which brings me to my next question. what size/pitch prop should this boat be running, and what is the max RPM's of this motor? being so old i can't find any info on it. we've taken it out twice and it turns 5200 rpm no problem, motor sounds like it can handle more. running a 3-blade 22 pitch prop, don't know diameter and it just feels slow. psi is 20+ running this way.

what is the min PSI when running wide open? should we just keep trying to trim it up? i have no idea about the shaft below pad thing. i know looking behind the boat while running down the lake, the hydrofoil is well out of the water and it doesn't appear that the motor is set too low.

but i don't know anything. trying to help out my stepdad so we can fish, dive, and tube behind it.

any input is appreciated.

[DJ from MN]

Hey reds, would like to put a name to this but your profile lacks a bunch of information. Anyhow, welcome to Cajun country.

I'm no expert, but will take a shot at what I have picked up from reading these boards.

If you prop for max speed, don't expect to do a decent job pulling a tube. Your prop diameter and pitch should be stamped either on the side of the prop or is on the hub behind or along side the nut. Seems to me those hammers want to run in the HIGH 5's or even 6 grand and I believe the WP should not fall below 12 psi at WOT. (You can check that out on the Yam forum)

Are you wide open at 5200 or are you backing off at 5200. Doesn't sound like enough prop to me.

If you really want to fine tune this thing you need to get to the Yam boards, and the set-up board. Todd is the pro at set-up and the Yam people will be happy to chip in with the answers.

[reds10]

Thanks, and yea, i left off quite a bit of info b/c i work for a boat company, not sure i want anyone knowing who i am yet :) And I can't afford a new boat right now so that why i don't have a new one of ours :)

the 5200 was WOT but it just didn't seem like all the power was there. motor was humming along just fine, no problems. Power is good, decent holeshot, very easy to blow out.

anyways, i'll post this over in the yam forum.


does anyone have any info about the boat? any specific problems with them? any way or place to get old parts? the dash could use replacing... :)

[CajunBass]

I would think that Yamaha should turn 55-5600, but that's relying on my old memory. Seems that's what most were supposed to turn. Might want to check your tach against a shop tach to make sure that's what you are turning.

Ummm Gee. He works for a boat company, and he lives in Arkansas. Wonder which one?

[AB]

Yamaha rated those engines to turn 4500-5500, just like all their others. Also, much like the newer ones, they came to life when propped to turn 5700-5800. Don't prop it to turn over 6000 if you leave the PrecisionBlend oiling hooked up.

Now.....That thing should turn a 22 well over 5200 on that rig unless it is a heavyass barge. When I had my old Yamaha, it was a 2.6 175 and would turn a 26 chopper to 6000 in stock form, to 6500 after I modded it...I also turned a 24 Performance Props Cleaver Drag to 7000 with it....but of course that was after the HydroTec Phase III kit went into her. Don't let your water pressure drop below 15psi.

Has the engine sat for any length of time? The old Yamaha carbs would gum up pretty quickly if you let them sit. The motor should really be run once per week, even if it is just for 5 minutes on the hose, or use a good quality stabalizer in the fuel. I would think something is amiss for it to turn those numbers. It should be able to turn that 22 to 5600-5700 with no problem. Also, the plug wires could cause a loss of rpm, a bad reed plate gasket (has that happen ), or a broken reed.....